Underground hydrogen storage warehouse structure of sandy soil combined flexible sealing layer and construction method of underground hydrogen storage warehouse structure

Abstract

The invention discloses an underground hydrogen storage bank structure of a sandy soil combined flexible sealing layer and a construction method of the underground hydrogen storage bank structure. The underground hydrogen storage bank structure comprises a cavern located in a surrounding rock body, a sandy soil layer, the flexible sealing layer, a plugging assembly and an injection-production chamber; the recesses / bulges on the inner wall of the cavern are filled to form a hydrogen storage space with a smooth inner surface; the flexible sealing layer is positioned in the hydrogen storage space and is used for storing and sealing hydrogen; the plugging assembly is located at the opening of the cavern and comprises a first plug used for plugging the cavern and a second plug used for plugging the flexible sealing layer, and the second plug is provided with a port for hydrogen input and output; the injection-production chamber is located on the side, away from the cavern, of the plugging assembly, and an injection-production assembly is arranged in the injection-production chamber so that injection-production of hydrogen can be achieved; the flexible sealing layer is used for replacing a traditional steel lining to seal hydrogen, the construction difficulty is lowered, and the requirement for construction precision is extremely low.

Description

Technical Field

[0001] The present application relates to the technical field of underground hydrogen storage, and in particular to an underground hydrogen storage structure with a sand-soil combined flexible sealing layer and a construction method thereof. Background Art

[0002] Hydrogen has the advantages of high energy density, long storage time, and environmental friendliness. It is very suitable as an energy storage medium. Using geological gas storage to store hydrogen for energy storage has become an important direction that needs to be explored in the current energy storage field because of its advantages such as small footprint, small environmental impact, and strong economy. However, the hydrogen stored in geological gas storage is in a high-pressure state (>10MPa), and it cannot rely on geological bodies to achieve gas sealing. Therefore, geological gas storage generally needs to be airtight. The most advanced method is to build a lined cave with a concrete-steel lining structure. The outer layer of this lined cave is the surrounding rock, which plays the role of bearing the air pressure. The inner layer is concrete, which plays the role of leveling and bearing part of the air pressure. The innermost layer is the steel lining, which is a sealing layer and plays a role in preventing gas leakage. However, this gas storage structure has huge problems in storing high-pressure hydrogen: (1) Construction is extremely difficult. my country's geological conditions are more suitable for the construction of horizontal geological hydrogen storage. When using a concrete-steel lining structure, it is necessary to solve problems such as anti-hydrogen embrittlement welding of the steel lining in an extremely narrow space, the production of steel mesh in an extremely narrow space, and the pouring and vibration of concrete in an extremely narrow space. These problems are all major construction difficulties, and there is currently no good construction method. (2) The construction precision is extremely high. Since the elastic strain range of the steel lining is extremely small, generally a few thousandths, when there are problems such as misalignment in the steel lining welding or voids in the concrete pouring, the steel lining is extremely likely to yield, promoting hydrogen embrittlement or direct fracture of the steel lining, resulting in failure of the steel lining's sealing performance. (3) The cost is extremely high. In order to reduce the possibility of hydrogen embrittlement of the steel lining in a high-pressure hydrogen environment, the steel lining must be made of materials such as 4130X. When the volume of the gas storage is large, the price of the steel lining alone is already very high. (4) Inevitable damage to the concrete lining: During the storage process of the hydrogen storage tank, since concrete is a brittle material that is not resistant to tension, significant cracks will inevitably appear in the concrete lining. This means that the sealing layer can only be made of high-strength metal materials. Using flexible materials will cause the sealing layer at the cracks to sag and then rupture. At the same time, the cracking of the concrete will cause stress concentration in the steel lining, causing damage to the steel lining. At the same time, during the repeated filling and degassing of the hydrogen storage tank, the repeated opening and closing of the concrete cracks will cause exaggerated fatigue damage.

[0003] (5) The requirements for the surrounding rock are very high. Since the concrete lining is directly bonded to the surrounding rock, cracks in the surrounding rock will induce strain concentration in the concrete, resulting in huge cracks. At the same time, if the surrounding rock grade is low, in order to fully utilize the bearing capacity of the surrounding rock, it is necessary to allow the surrounding rock to deform significantly, which will cause serious damage to the concrete lining.

[0004] (6) Safety is not guaranteed; the steel lining is prone to hydrogen embrittlement under high strain conditions, causing the sealing layer to fail; (7) The weight and strength of the surrounding rock cannot be fully utilized; the surrounding rock has low rigidity due to the presence of cracks. When the degree of cracking of the concrete lining needs to be controlled, the surrounding rock cannot be allowed to move significantly. This requires increasing the thickness and strength of the concrete and reducing the load on the surrounding rock. Therefore, the bearing capacity of the surrounding rock cannot be effectively utilized, which increases the construction cost. Therefore, a new underground hydrogen storage structure is urgently needed to solve the above-mentioned problems existing in the concrete-steel lined gas storage. Summary of the Invention

[0005] In order to solve the above problems, the present application provides an underground hydrogen storage structure with a sand-soil combined flexible sealing layer, which reduces the construction difficulty and construction precision requirements, gives full play to the role of the surrounding rock, and improves the applicability of the hydrogen storage to geological conditions. The technical solution is as follows: The first aspect of the present application provides an underground hydrogen storage structure with a sand-soil combined flexible sealing layer, comprising a cavern located in a surrounding rock mass, a sand layer, a flexible sealing layer, a plugging assembly and an injection-production chamber, wherein the sand layer is attached to the inner wall surface of the cavern to fill the depressions / protrusions on the inner wall of the cavern to form a hydrogen storage space with a smooth inner surface; the flexible sealing layer is located in the hydrogen storage space and is used to store and seal hydrogen; the plugging assembly is located at the opening of the cavern, and comprises a first plug for sealing the cavern and a second plug for sealing the flexible sealing layer, and a port for hydrogen input and output is provided on the second plug; the injection-production chamber is located on a side of the plugging assembly away from the cavern, and an injection-production assembly is provided in the injection-production chamber to realize the injection and production of hydrogen sealed and stored in the flexible sealing layer.

[0006] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, the flexible sealing layer is a polymer airbag, and the polymer airbag can expand and squeeze the sand layer to adjust the shape of the sand layer.

[0007] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, the first plug is a wedge-shaped concrete plug embedded in the surrounding rock body to form a sealed space with the surrounding rock body and provide a reaction force for the flexible sealing layer.

[0008] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, the second plug is an airbag plug, which is attached to the side of the first plug facing the injection and production chamber to seal the opening of the polymer airbag, and an airbag airway passing through the first plug is provided at the airbag opening, and a hydrogen output hole and a hydrogen input hole connected to the airbag airway are provided in the center of the second plug, and a plurality of bolt holes are arranged around the outer circle of the second plug.

[0009] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, the sealing assembly also includes a plurality of embedded bolts, the embedded bolts including a stud, a nut and a clamping portion, the stud passes through the first plug and passes out from the bolt hole on the second plug to press the second plug onto the first plug, the nut is provided at the free end of the stud extending out of the bolt hole, and the clamping portion is provided at the end of the stud away from the free end and is fixedly connected to the surrounding rock body.

[0010] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, the injection and production assembly includes a hydrogen output pipeline and a hydrogen input pipeline, the hydrogen output pipeline is connected to the hydrogen output hole, the hydrogen input pipeline is connected to the hydrogen input hole, a gas pressure reducing pump is provided on the hydrogen output pipeline, and a gas boosting pump is provided on the hydrogen input pipeline.

[0011] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, a plurality of concentric raised rings with the center of the second plug as the center are provided on the surface of the second plug facing the injection and production chamber.

[0012] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, a partition wall and a sealed explosion-proof door are also included, and the partition wall and the sealed explosion-proof door are located between the injection and production chamber and the sealing assembly.

[0013] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, a hydrogen concentration monitor is provided on the side of the partition wall and the sealed explosion-proof door facing the sealing assembly to monitor hydrogen leakage from the hydrogen storage in real time.

[0014] A second aspect of the present application provides a construction method for an underground hydrogen storage structure comprising a sand-soil combined flexible sealing layer, comprising the following steps: S1 Excavate a cavern of the required volume in the surrounding rock or directly use the abandoned cavern formed by mining; S2 fills the inner wall of the cavern with sand and soil layers to construct a hydrogen storage space similar to the shape of a polymer airbag: first fill the sand and soil layer below the cavern bottom, then fill the sand and soil layer above the cavern bottom, and finally fill the sand and soil layer below the cavern opening; S3 places the polymer airbag into the hydrogen storage space and unfolds it, blocks the airway of the airbag after inflation, and expands the polymer airbag to have the load-bearing capacity; S4 fills the sand layer above the cavern opening to complete the construction of the sand layer; S5: pour concrete first plug at the cavern opening and pre-place embedded bolts and airbag air duct in the first plug; S6: Place the second plug on the first plug, insert the stud of the embedded bolt into the bolt hole on the second plug, and tighten the nut; S7: Install the hydrogen output pipe and the hydrogen input pipe, connect the hydrogen output pipe to the hydrogen output hole on the second plug, and connect the hydrogen input pipe to the hydrogen input hole on the second plug; S8: Install a gas pressure reducing pump on the hydrogen output pipeline and a gas pressure boosting pump on the hydrogen input pipeline; S9 installed hydrogen concentration monitors, partition walls and sealed explosion-proof doors in the injection and production room to complete the structural construction of the hydrogen storage tank.

[0015] The beneficial effects brought about by an underground hydrogen storage structure and a construction method of a sand-soil combined flexible sealing layer provided in some embodiments of the present application are as follows: the present application establishes a geological hydrogen storage structure of surrounding rock-sand layer-flexible sealing layer, and uses polymer airbags as flexible sealing layers instead of traditional steel liners to seal hydrogen, which reduces the construction difficulty and has extremely low requirements for construction precision. The structure is simple, the construction cost is reduced, the safety is improved, and the applicability of the hydrogen storage to geological conditions is improved. The role of the surrounding rock is fully utilized, the sand layer is used to achieve leveling of the surrounding rock, lubricates the relative slip between the surrounding rock and the flexible sealing layer, and buffers the strain concentration of the flexible sealing layer caused by cracking of the surrounding rock. Concrete plugs and embedded bolts are used to achieve sealing between the polymer airbags and the airbag plugs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of this specification or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a schematic diagram of the overall structure of the underground hydrogen storage structure with a sand-soil combined flexible sealing layer of the present application; Figure 2 This is a schematic diagram of the second plug structure of this application; Figure 3 This is a side view of the second plug of this application; Figure 4 This is a schematic diagram of the embedded bolt structure of this application; Figure 5 Schematic diagram of the sand layer structure of this application. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0019] Unless otherwise defined, the technical or scientific terms used in this disclosure should have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words "first", "second" and similar terms used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0020] The first aspect of the present application provides an underground hydrogen storage structure with a sand-soil combined flexible sealing layer, such as Figure 1 As shown, it includes a cavern 200, a sand layer 300, a flexible sealing layer 400, a sealing assembly 500 and an injection and production chamber 600 located in the surrounding rock mass 100, the sand layer 300 is attached to the inner wall surface of the cavern 200 to fill the depression / protrusion of the inner wall of the cavern 200 to form a hydrogen storage space with a smooth inner surface; the flexible sealing layer 400 is located in the hydrogen storage space and is used to store and seal hydrogen; the sealing assembly 500 is located at the opening of the cavern 200, including a first plug 510 for sealing the cavern 200 and a second plug 520 for sealing the flexible sealing layer 400, and a port for hydrogen input and output is provided on the second plug 520; the injection and production chamber 600 is located on the side of the sealing assembly 500 away from the cavern 200, and an injection and production assembly 610 is provided in the injection and production chamber 600 to realize the injection and production of the hydrogen sealed and stored in the flexible sealing layer 400.

[0021] The surrounding rock mass 100 plays the role of bearing the gas pressure and is responsible for balancing the high-pressure gas inside the reservoir by utilizing its shear strength, tensile strength and its own weight.

[0022] The sand layer 300 plays the role of leveling, lubrication, buffering and force transmission, as follows: (1) Generally speaking, the surface of a mine left by mining is extremely uneven. Even for a cavern excavated specifically for a hydrogen storage tank, it is difficult to make the surrounding rock surface approximately flat. The sand layer can fill the depressions and protrusions on the surrounding rock surface of the inner wall of the cavern 200 and play a certain lubricating role, so that the flexible sealing layer 400 will not be damaged by friction due to relative sliding on the rough surface.

[0023] (2) There are inevitably cracks in the surrounding rock mass 100. When the hydrogen storage reservoir is inflated, the reservoir expands and the cracks open. At this time, the sand layer 300 will buffer the strain concentration of the flexible sealing layer 400 caused by the cracks.

[0024] (3) Although the strength of the sand layer 300 is extremely low, the surrounding rock mass 100 and the first plug 510 form a closed space from which the sand layer 300 cannot flow out. Therefore, the sand layer 300 can effectively transmit the restraining effect of the surrounding rock mass 300 on the flexible sealing layer 400, and transmit the reaction force to limit the large deformation of the highly flexible sealing layer 400 caused by inflation.

[0025] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 1 As shown, the flexible sealing layer 400 is a polymer airbag, which can expand and squeeze the sand layer 300 to adjust the shape of the sand layer 300.

[0026] The function of the flexible sealing layer 400 is to seal hydrogen. The polymer airbag 400 is used to describe the flexible sealing layer below. Specifically, due to the load-bearing part, the polymer airbag 400 will not produce significant deformation and only plays the role of sealing hydrogen. The polymer airbag 400 can be made of polymer materials such as rubber and polyurethane, and can be formed into an integrated shape by extrusion or casting. Alternatively, a polymer sheet can be first made and then welded to form an integrated airbag. The polymer airbag 400 has excellent ductility and a yield strain generally exceeding 10%. Therefore, it does not need to fit tightly with the sand layer 300. When the air pressure increases, the polymer airbag 400 expands and squeezes the sand layer 300. Since the sand layer 300 has very low strength and a certain fluidity, the shape of the sand layer 300 can be automatically adjusted to adapt to the polymer airbag 400.

[0027] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 1As shown, the first plug 510 is a wedge-shaped concrete plug embedded in the surrounding rock mass 100 to form a sealed space together with the surrounding rock mass 100 and provide a reaction force for the flexible sealing layer 400 .

[0028] Among them, the first plug 510 is a concrete plug, which is a wedge-shaped body embedded in the surrounding rock. The wedge shape can enhance the connection between the first plug 510 and the surrounding rock body 100. The first plug 510 and the surrounding rock body 100 form a sealed space to provide a reaction force for the polymer airbag 400.

[0029] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 2-3 As shown, the second plug 520 is an airbag plug, which is attached to the side of the first plug 510 facing the injection chamber 600 to seal the opening of the polymer airbag 400. An airbag airway 410 that passes through the first plug 510 is provided at the opening of the polymer airbag 400. A hydrogen output hole 521 and a hydrogen input hole 522 that are connected to the airbag airway 410 are provided at the center of the second plug 520. Several bolt holes 523 are arranged around the outer circle of the second plug 520.

[0030] Among them, the function of the second plug 520 is to seal the opening of the polymer airbag 400 and provide ports for hydrogen input and output. The second plug 520 is made of hydrogen-resistant metal such as 4130X, and is surrounded by several bolt holes 523 near the outer circle. The second plug 520 is the only hydrogen-facing metal structure of the hydrogen storage reservoir and is located outside the reservoir, which can be easily replaced and damaged.

[0031] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 4 As shown, the sealing assembly 500 also includes a plurality of embedded bolts 530, and the embedded bolts 530 include a stud 531, a nut 532 and a pressing portion 533. The stud 531 passes through the first plug 510 and passes out from the bolt hole 523 on the second plug 520 to press the second plug 520 onto the first plug 510. The nut 532 is provided at the free end of the stud 531 extending out of the bolt hole 523, and the pressing portion 533 is provided at the end of the stud 531 away from the free end and is fixedly connected to the surrounding rock body 100.

[0032] Specifically, the function of the embedded bolt 530 is to press the second plug 520 tightly onto the first plug 510. The embedded bolt 530 passes through the concrete first plug 510. The clamping part 533 of the stud 531 is a pancake. Most of the embedded bolt 530 is cast in the concrete first plug 510. The stud 531 passes through the bolt hole 523 on the second plug 520 and tightens the nut 532. The bonding force between the embedded bolt 530 and the concrete first plug 510 and the reaction force of the internal pancake-shaped clamping part 533 are used to achieve the clamping of the second plug 520.

[0033] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 1 As shown, the injection and production component 610 includes a hydrogen output pipeline 611 and a hydrogen input pipeline 612. The hydrogen output pipeline 611 is connected to the hydrogen output hole 521, and the hydrogen input pipeline 612 is connected to the hydrogen input hole 522. A gas pressure reducing pump 613 is provided on the hydrogen output pipeline 611, and a gas boosting pump 614 is provided on the hydrogen input pipeline 612.

[0034] The hydrogen output pipeline 611 connects the hydrogen user, the gas pressure reducing pump 613, and the hydrogen output hole 521 on the gas bag plug (second plug 520). It is made of 4130X steel, which is also convenient for replacement and monitoring. The hydrogen input pipeline 612 connects the hydrogen generator, the gas booster pump 614, and the hydrogen input hole 522 on the gas bag plug (second plug 520). It is also made of 4130X steel, which is also convenient for replacement and monitoring. The gas pressure reducing pump 613 extracts hydrogen from the hydrogen storage and reduces the pressure to the target value so that the hydrogen meets the needs of the hydrogen user. The gas booster pump 614 collects hydrogen produced by upstream industries, increases the pressure to the target value, and injects the hydrogen into the hydrogen storage. The gas pressure reducing pump 613 and the gas booster pump 614 are directly connected to the hydrogen storage via pipelines. They have the function of monitoring the air pressure in the pipelines and can record the changes in air pressure to evaluate the sealing of the hydrogen storage.

[0035] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 2-3 As shown, a plurality of concentric raised rings 524 with the center of the second plug 520 as the center are provided on the surface of the second plug 520 facing the injection chamber 600.

[0036] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 1 As shown, a partition wall and a sealed explosion-proof door 700 are also included, and the partition wall and the sealed explosion-proof door 700 are located between the injection and production chamber 600 and the blocking assembly 500.

[0037] The partition wall and sealed explosion-proof door 700 further separate the hydrogen storage reservoir from conventional working areas such as powered equipment and the injection and extraction chamber 600. If a slight leak occurs at the airbag plug, or second plug 520, the partition wall and sealed explosion-proof door 700 can confine the leaking hydrogen to a smaller space, facilitating detection. Furthermore, they prevent factors such as sparks within the injection and extraction chamber 600 from affecting the hydrogen storage reservoir.

[0038] For example, in the underground hydrogen storage structure of the sand-soil combined flexible sealing layer provided in one embodiment, Figure 1 As shown, a hydrogen concentration monitor 800 is provided on the side of the partition wall and the sealed explosion-proof door 700 facing the blocking assembly 500 to monitor the hydrogen leaked from the hydrogen storage tank into the tunnel in real time, thereby providing safety protection for the hydrogen storage tank.

[0039] A second aspect of the present application provides a construction method for an underground hydrogen storage structure comprising a sand-soil combined flexible sealing layer, comprising the following steps: S1 excavates a cavern 200 of the required volume in the surrounding rock or directly uses an abandoned cavern formed by mining; A cavern 200 of the required volume is excavated in the surrounding rock. This construction method has no requirements on the roughness of the inner surface of the cavern 200 or on over-excavation or under-excavation, thus reducing excavation costs. Directly use the abandoned caverns formed by mining to recycle waste and deal with the safety hazards caused by the abandoned caverns.

[0040] S2 fills the inner wall of the cavern 200 with a sand layer 300 to construct a hydrogen storage space similar to the shape of a polymer airbag 400: Figure 5 As shown, first fill the sand layer 310 below the cave bottom, then fill the sand layer 320 above the cave bottom, and then fill the sand layer 330 below the cave opening; The hydrogen storage structure of the present application does not require high precision of the sand layer 300 and can be constructed using the following two methods: (1) Sand is mixed with a certain amount of clay soil or other adhesives, and the space of the chamber is directly filled to create the approximate shape of the polymer airbag 400; (2) Sand and soil are mixed with a certain amount of clay or other adhesives, and the surrounding rock is leveled in the cave. Large-volume sand and soil blocks with extremely low strength are made in an open area or a processing plant, and the sand and soil blocks are used to fill the cavern space to build the approximate shape of the polymer airbag 400.

[0041] S3: Place the polymer airbag 400 into the hydrogen storage space and unfold it. After a brief inflation, seal the airbag airway 410, so that the polymer airbag 400 expands to have a slight load-bearing capacity. S4 fills the sand layer 340 above the cavern opening to complete the construction of the sand layer 300; S5: Pour a first concrete plug 510 at the opening of the cavern 200, and pre-place embedded bolts 530 and the airbag air channel 410 in the first plug 510. Install the steel cage of the first concrete plug 510, set up a customized template outside the first concrete plug 510, pour concrete in the space formed by the template, sand layer, and surrounding rock, and wait for the concrete to solidify. S6: Remove the template, place the second plug 520 on the first plug 510, insert the stud 531 of the embedded bolt 530 into the bolt hole 523 on the second plug 520, and tighten the nut 532; S7: Install the hydrogen output pipe 611 and the hydrogen input pipe 612, connect the hydrogen output pipe 611 to the hydrogen output hole 521 on the second plug 520, and connect the hydrogen input pipe 612 to the hydrogen input hole 522 on the second plug 520; S8: Install a gas pressure reducing pump 613 on the hydrogen output pipeline 611 and a gas pressure boosting pump 614 on the hydrogen input pipeline 612; S9 installs a hydrogen concentration monitor 800, a partition wall, and a sealed explosion-proof door 700 in the injection and production chamber 600 to complete the construction of the hydrogen storage structure.

[0042] The construction method of the underground hydrogen storage structure with a soil-combined flexible sealing layer of the present application reduces the construction difficulty, avoids the use of many unfeasible construction methods that occur when using the current concrete-steel lining structure, reduces the construction precision requirements, has high safety, gives full play to the role of the surrounding rock, and avoids the use of expensive construction materials, thereby reducing construction costs; improves the applicability of the hydrogen storage to geological conditions, has extremely low requirements for geological conditions, and can directly transform abandoned caverns such as mines into hydrogen storage; avoids the use of concrete materials, thereby avoiding the cracks that are inevitably produced in traditional concrete lining structure hydrogen storage tanks, avoids the use of metal materials, avoids the occurrence of hydrogen embrittlement, and improves safety.

[0043] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An underground hydrogen storage structure with a sand-soil combined flexible sealing layer, characterized in that: include: Caverns located in the surrounding rock mass: A sand layer is attached to the inner wall of the cavern to fill the depressions / protrusions on the inner wall of the cavern to form a hydrogen storage space with a smooth inner surface; a flexible sealing layer, located in the hydrogen storage space, for storing and sealing hydrogen; a plugging assembly located at the opening of the cavern, comprising a first plug for sealing the cavern and a second plug for sealing the flexible sealing layer, wherein the second plug is provided with ports for hydrogen input and output; The injection and production chamber is located on a side of the plugging component away from the cavern. An injection and production component is provided in the injection and production chamber to realize the injection and production of hydrogen sealed and stored in the flexible sealing layer.

2. The underground hydrogen storage structure with sand and soil combined with a flexible sealing layer according to claim 1, characterized in that: The flexible sealing layer is a polymer airbag, which can expand and squeeze the sand layer to adjust the shape of the sand layer.

3. The underground hydrogen storage structure of the sand-soil combined flexible sealing layer according to claim 2 is characterized in that: The first plug is a wedge-shaped concrete plug embedded in the surrounding rock mass to form a sealed space together with the surrounding rock mass and provide a reaction force for the flexible sealing layer.

4. The underground hydrogen storage structure of the sand-soil combined flexible sealing layer according to claim 3 is characterized in that: The second plug is an airbag plug, which is attached to the side of the first plug facing the injection chamber to seal the opening of the polymer airbag. An airbag airway running through the first plug is provided at the airbag opening. A hydrogen output hole and a hydrogen input hole connected to the airbag airway are provided in the center of the second plug. Several bolt holes are arranged around the outer circle of the second plug.

5. The underground hydrogen storage structure of the sand-soil combined flexible sealing layer according to claim 4 is characterized in that: The sealing assembly also includes a plurality of embedded bolts, each of which includes a stud, a nut, and a pressing portion. The stud passes through the first plug and passes out from the bolt hole on the second plug to press the second plug onto the first plug. The nut is provided at the free end of the stud extending out of the bolt hole. The pressing portion is provided at the end of the stud away from the free end and is fixedly connected to the surrounding rock body.

6. The underground hydrogen storage structure of the sand-soil combined flexible sealing layer according to claim 7 is characterized in that: The injection and production assembly includes a hydrogen output pipeline and a hydrogen input pipeline. The hydrogen output pipeline is connected to the hydrogen output hole, and the hydrogen input pipeline is connected to the hydrogen input hole. A gas pressure reducing pump is provided on the hydrogen output pipeline, and a gas boosting pump is provided on the hydrogen input pipeline.

7. The underground hydrogen storage structure with sand and soil combined with a flexible sealing layer according to claim 6, characterized in that: A plurality of concentric raised circular rings with the center of the second plug as the center are provided on the surface of the second plug facing the injection chamber.

8. The underground hydrogen storage structure with sand and soil combined with a flexible sealing layer according to claim 7, characterized in that: It also includes a partition wall and a sealed explosion-proof door, which are located between the injection and production chamber and the blocking assembly.

9. The underground hydrogen storage structure with sand and soil combined with a flexible sealing layer according to claim 8, characterized in that: A hydrogen concentration monitor is provided on the side of the partition wall and the sealed explosion-proof door facing the blocking assembly to monitor the hydrogen leakage from the hydrogen storage tank in real time.

10. The construction method of the underground hydrogen storage structure with sand-soil combined flexible sealing layer according to claim 9 is characterized in that: The following steps are involved: S1 Excavate a cavern of the required volume in the surrounding rock or directly use the abandoned cavern formed by mining; S2 fills the inner wall of the cavern with sand and soil layers to construct a hydrogen storage space similar to the shape of a polymer airbag: first fill the sand and soil layer below the cavern bottom, then fill the sand and soil layer above the cavern bottom, and finally fill the sand and soil layer below the cavern opening; S3 places the polymer airbag into the hydrogen storage space and unfolds it, blocks the airway of the airbag after inflation, and expands the polymer airbag to have the load-bearing capacity; S4 fills the sand layer above the cavern opening to complete the construction of the sand layer; S5: pour concrete first plug at the cavern opening and pre-place embedded bolts and airbag air duct in the first plug; S6: Place the second plug on the first plug, insert the stud of the embedded bolt into the bolt hole on the second plug, and tighten the nut; S7: Install the hydrogen output pipe and the hydrogen input pipe, connect the hydrogen output pipe to the hydrogen output hole on the second plug, and connect the hydrogen input pipe to the hydrogen input hole on the second plug; S8: Install a gas pressure reducing pump on the hydrogen output pipeline and a gas pressure boosting pump on the hydrogen input pipeline; S9 installed hydrogen concentration monitors, partition walls and sealed explosion-proof doors in the injection and production room to complete the structural construction of the hydrogen storage tank.

Images